236 STRONG. 



employed the reaction in the diagnosis of glanders, using a glycerine-free culture 

 liltrate of Bacillus mulld added to the serum of the glandered horse. The em- 

 ployment of the reaction with sera prepared by injecting into one animal certain 

 albuminous bodies of another one lias also proved of great value for diagnostic 

 purposes, and in some instances a very delicate test. Thus Wassermann and 

 Ulilenhuth,-' with proper immune sera, showed that a speeilic precipitin reaction 

 might he obtained against the dissolved albuminous substances in human blood 

 in the dilution of 1 to 50,1101). The precipitins have been proved to be absolutely 

 specific against those of unrelated species, although they sometimes react on 

 closely related albumens. The reaction has also been employed for the differentia- 

 tion of other microorganisms, including bovine and human strains of tubercule 

 bacilli and even for the various species of trypanosomata, with varying results. 

 Shortly after my experiments were begun with the precipitin test in the diagnosis 

 of the spirochsetai of relapsing fever, the work of Fornet, Shereschewsky, Eisen- 

 zimmer and Rosenfeld,"' on the subject of "Spezifische NiederschHige bei Lues 

 Tabes und Paralyse" appeared. These authors found that upon mixing the 

 serum from acute cases of syphilis with that from cases of the same disease of 

 long standing, with tabetic and paralytic symptoms, that a precipitin was 

 obtained. They believed that in the more acute cases of syphilis, those in which 

 spirochartse were found to be present, the precipitinogen was present in the serum 

 and that in the older cases of long standing the precipitin existed. They employed 

 the ring test for these reactions, placing the heavier serum at the bottom of a 

 small test tube and adding gradually the lighter serum in a layer on top. At 

 the junction of the two sera in the case of a positive reaction, the precipitate 

 appeared as a narrow band or ring. Still more recently Michaelis -° has reported 

 that he obtained a specific precipitin reaction with the blood sera in cases of 

 syphilis, employing an extract of the liver as the solution containing the 

 precipitinogen. 



The experiments to be recorded here were conducted with two strains 

 of spirochasta?, one obtained from Africa and the other from America. 

 At first the precipitin reactions were carried on in small, conical reagent- 

 glasses by mixing the serum supposed to contain an excess of precipi- 

 tinogen with the immune serum supposed to contain an excess of 

 precipitin. The resulting mixture was then compared with one con- 

 sisting of the first serum to which a normal serum had been added. 

 After reading the article of Fornet and his colleagues, the reactions 

 were carried on by superimposing one serum upon the other, as was 

 suggested by these authors, the second serum being allowed to flow down 

 the side of the reagent glass from a capillary pipette until a layer of 

 equal thickness to that of the first below had been introduced. Care was 

 taken to observe that the blood from which the serum was separated and 

 used for the precipitin contained no spirocha?tse which could be detected 

 by microscopical examination, both before and at the time the blood was 

 collected for the test, and that the blood from which the serum was 

 separated for use as the precipitinogen contained numerous parasites. 



:4 hoe. cit., 594. 



"'Deutsche med. Wehitseh. (1907), 33, 1079. 



""Berl. him. Wchitsch. (1907), 44, 1477. 



